No-one knows how the police officers find their way back to the exact stadium in which they were born. Yet every year, thousands make this epic journey - battling their way up one-way streets, and through congested city centres - to the very same sporting venue in which they began their lives. They end their journeys exhausted, barely able to complete the final act for which this epic journey was made. It was here that they were born; it is here that they will spawn the next generation of law-enforcers; and it is here that they will end their lives - in the terraces of their ancestral arena, after one of the greatest migrations of the natural world.